This invention relates to a disk cartridge, such as a floppy disk, containing a magnetic disk medium and to a method of manufacturing the same.
A conventional disk cartridge comprises a magnetic disk medium and upper and lower shells forming a space to receive the magnetic disk medium. The upper and the lower shells are provided with upper and lower head windows, respectively, to permit access to the magnetic disk medium by a pair of magnetic heads. The magnetic disk medium is made of a magnetic material having flexibility. A liner is attached to an inner surface of each of the upper and the lower shells. The liner serves to remove fine dust attracted onto the surface of the magnetic disk medium. Therefore, the liner is preferably arranged as close as possible to the surface of the magnetic disk medium.
The conventional disk cartridge has a first problem in that the magnetic disk medium is readily wrinkled as will later be described in detail.
Furthermore, the conventional disk cartridge has go a second problem in that, if the liner is too close to the magnetic disk medium, a torque loss will be caused to reduce a torque for rotating the magnetic disk medium. With an increase in torque loss, data writing/reading operations upon the magnetic disk medium become unstable and unreliable.
On the other hand, an apparatus for accessing the disk cartridge described above by the use of magnetic heads is called a disk drive. The disk drive comprises a disk holder unit for receiving the disk cartridge, and upper and lower magnetic heads for accessing the magnetic disk medium through the upper and the lower head windows of the disk cartridge. The upper and the lower magnetic heads are held by a carriage assembly.
More specifically, the carriage assembly comprises upper and lower carriages. The upper and the lower carriages hold the upper and the lower magnetic heads at their top ends, respectively. If no disk cartridge is received in the disk drive, it is necessary to separate the upper magnetic head from the lower magnetic head. For this purpose, when no disk cartridge is received in the disk drive, an arm attached to the upper carriage is engaged with the disk holder unit so that the top end of the upper carriage is lifted up. It is noted here that the disk cartridge has a thickness of about 3.3 mm if it is a floppy disk. Therefore, in the conventional disk drive for the floppy disk, the top end of the upper carriage must be lifted up in a range between about 3.5 and 3.6 mm. Thus, in the disk drive for the disk cartridge, the upper magnetic head must be displaced over a distance greater than the thickness of the disk cartridge. For this purpose, a vertical movement mechanism for vertically moving the upper magnetic head is required. The vertical movement mechanism is subjected to a heavy load. Since the displacement of the upper magnetic head is relatively large, a head load pressure downwardly applied to the upper magnetic head is not stable. This third problem results from the structure of the disk cartridge.
It is therefore a first object of this invention to provide a disk cartridge capable of suppressing the occurrence of wrinkles on a magnetic disk medium.
It is a second object of this invention to provide a method of manufacturing a disk cartridge capable of suppressing the occurrence of wrinkles on a magnetic disk medium.
It is a third object of this invention to provide a disk cartridge capable of reducing a torque loss due to the presence of a liner so as to stably and reliably carry out writing/reading operations.
It is a fourth object of this invention to provide a disk cartridge capable of minimizing a vertical displacement of an upper magnetic head of a disk drive.
It is a fifth object of this invention to provide a disk cartridge capable of readily stabilizing head load pressure applied to an upper magnetic head of a disk drive.
A disk cartridge according to this invention comprises a magnetic recording medium which includes a magnetic disk medium having an annular shape with a circular opening formed at its center and a metal hub supporting the magnetic disk medium. The metal hub comprises a cylindrical portion fitted into the circular opening and a flange portion formed at the upper end of the cylindrical portion. A lower surface of the flange portion is adhered to an upper surface of the magnetic disk medium at the periphery of the circular opening.
According to a first aspect of this invention, the disk cartridge further comprises an annular reinforcing member adhered to a lower surface of the magnetic disk medium at the periphery of the circular opening.
A method of manufacturing a disk cartridge according to this invention comprises the steps of preparing a disk-shaped magnetic disk medium having a first diameter defined by a first center, preparing a disk-shaped reinforcing member having a second diameter smaller than the first diameter and defined by a second center, adhering the reinforcing member to the lower surface of the magnetic disk medium with the first and the second centers coincident with each other, removing a center portion of the magnetic disk medium with the reinforcing member adhered thereto to form a circular opening having a third diameter smaller than the second diameter, preparing a metal hub comprising a cylindrical portion having a fourth diameter smaller than the third diameter and a flange portion formed at the upper end of the cylindrical portion and having a fourth diameter greater than the third diameter, and fitting the cylindrical portion into the circular opening of the magnetic disk medium on the side of the upper surface thereof and adhering the lower surface of the flange portion and the upper surface of the magnetic disk medium at the periphery of the circular opening.
A disk cartridge according to this invention comprises a jacket body receiving a magnetic disk medium and having a head window permitting a magnetic head to access the magnetic disk medium, and upper and lower liners adhered to upper and lower inner surfaces of the jacket body, respectively, to remove fine dust attracted to the upper and the lower surfaces of the magnetic disk medium. A distance h0 is kept between the upper and the lower liners.
According to a second aspect of this invention, a distance h1 smaller than the distance h0 is kept between the upper and the lower liners at the periphery of the circular opening at least on an upstream side of the head window with respect to a rotating direction of the magnetic disk medium.
A disk cartridge according to this invention comprises a jacket body receiving a magnetic disk medium and having upper and lower head windows permitting a pair of magnetic heads to access the magnetic disk medium, and a shutter for opening and closing the upper and the lower head windows. The jacket body comprises upper and lower shells.
According to a third aspect of this invention, the upper and the lower head windows are formed by upper and lower notches formed in the upper and the lower shells, respectively. The shutter has a shutter window for exposing the upper and the lower head windows. The shutter window is formed by cutting upper, lower, and front surfaces of the shutter at positions corresponding to the upper and the lower head windows.